A general notion of the Siemens’ regenerative stove will have been already gained from the account given before of its application to the modern type of blast furnace. Of the inventor himself, C. William Siemens, it may be observed that he was one of a family of brothers, all remarkable for their scientific attainments, and in many of his researches and processes he was aided by his brothers Frederick and Otto. In our article on “Electric Power and Lighting” there will be found some notice of a few of Siemens’ inventions pertaining to those subjects. A still more admirable invention of his is the electric pyrometer, an instrument of the utmost utility for measuring, with an accuracy previously unapproachable, the high temperature of furnaces, etc. Indeed there are few departments of science, pure or applied, which have not been enriched by the researches and contrivances of this distinguished man, whose merits were acknowledged by the bestowal upon him of the highest scientific and academical honours, and also of a title, for he became Sir William Siemens. [Illustration: FIG. 26.—_Section of Regenerative Stoves and Open Hearth._ ] Siemens was much engaged from 1846 in conjunction with his brother Frederick in experimental attempts, continued over a period of ten years, at the construction of the regenerative gas furnace. At length, in 1861, he proposed the application of his furnace to an “open hearth,” and during the next few years some partial attempts to carry out his process were made, and he himself had established experimental works at Birmingham in order to mature his processes, while Messrs. Martin of Sireuil, in France, having obtained licences under Siemens’ patents, gave their attention to a modification of his process, by which they succeeded in producing excellent steel. Siemens having in 1868 proved the practicability of his plans by converting at his Birmingham works some old phosphorized iron rails into serviceable steel, a company was formed, and in 1869 the Landore Siemens’ Steel Works were established at Landore in Glamorganshire, and a few years after, these had sixteen Siemens open hearth melting furnaces at work, giving a total output of 1,200 tons of steel per week. The number of furnaces was subsequently increased. Extensive works specially designed for carrying out the Siemens and the Siemens-Martin process were shortly afterwards erected at other places, as at Newtown, near Glasgow, Panteg in Wales, etc. In Great Britain the open hearth process gradually gained upon the Bessemer, until in 1893, when the total output of both kinds amounted to nearly 3,000,000 tons, this was almost equally divided between them, and since that period the steel made by the former has greatly surpassed in amount that made by the latter.